could be signal issues as well, if the line amps are not configured correctly the temperature compensation could be off and your upstream/downstream snr could be going to shit at night, this would be unusual because usually its daytime snr issues being the problem due to ..well solar radiation, higher EM noise floors, but if they are overcompensating at night, it would explain your snr going to shit.
don't take this as facts, i've not done a whole lot on the rf side, but its worth checking into.
don't take this as facts, i've not done a whole lot on the rf side, but its worth checking into.